Radiological evaluation of reduction loss in unstable proximal humeral fractures treated with locking plates

PurposeThe aim of this study was to radiologically evaluate the risk of reduction loss after locking plate fixation of proximal humerus fractures.MethodsFrom September 2007 to April 2009, 71 patients (28 males, 43 females) with unstable proximal humeral fracture were treated with open reduction and internal fixation by locking plate. The mean follow-up time was 31.2 months (range: 26–47). The head-shaft angulation (HSA) and the humeral head height (HHH) in true anteroposterior (AP) were recorded and compared over time. All complications were noted. Shoulder function was measured by the Constant score.ResultsPatients with ΔHSA >10° (t = 2.740, P = 0.008) and ΔHHH >5 mm (t = 2.55, P = 0.019) were more likely to have impaired shoulder function. Varus collapse occurred most frequently in patients with initial reduction of HSA <125° (χ2=19.17, P<0.001, Fisher's exact test F<0.001). Patients with >5 mm HHH decrease were strongly associated with loss of reduction (χ2 = 24.23, P<0.001, F<0.001).ConclusionsDynamic change of HSA >10° and HHH >5 mm were radiological factors that indicated poor shoulder function. Intra-operative HSA >125° should be achieved to avoid reduction loss following locking plate fixation of proximal humerus fracture.Level of evidencelevel IV.